A computerized travel system is organized around a Global Distribution System GDS being accessed by travel vendors such as travel agencies, online travel vendors and travel companies. The GDS system may be a proprietary computer system allowing real-time access to airline fares, schedules, and seating availability and other data.
The GDS system implements an access to various data sources in order to provide availability information. The accessed data sources may be remote from the GDS system. They may be data sources provided by airlines. To retrieve availability information, an inventory source can be accessed by polling while other data sources are accessible in parallel in order to reduce the polling bandwidth, save costs (inventory database's accesses are more expensive) and cut off response time as often as possible.
A challenge is to quickly react to a rapid variation such as a growth of computation inquiries or a crisis (like a polling outage) and meanwhile to maintain the data access efficiency of data sources. It leads to technical constraints involving routing decisions between various sources where data relevant to reply to an availability request are potentially stored. System must then decide in which case it is more appropriate to use an AVS (availability status source) or a cache data source.
James Aweya et al. disclose in “An adaptive load balancing scheme for web servers”, International Journal of Network Management, vol. 12, no. 1, 1 Jan. 2002, pages 3-39 an admission control function in a web switch combined to a load balancing scheme for routing incoming requests to a plurality of web servers. The web servers periodically send server health status information to the web switch.